Internet Protocol version 6 (IPv6) is the next-generation Internet working protocol version designated as the successor to IPv4. IPv4 is the first implementation used in the Internet and is still widely used. IPv6 has a vastly larger address space than IPv4. This results from the use of a 128-bit address, whereas IPv4 uses only 32 bits. This expansion provides flexibility in allocating addresses and routing traffic and eliminates the need for network address translation (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion.
IPv6 does not implement traditional IPv4 broadcast and does not use any special broadcast address for transmitting a packet to all hosts on an attached physical link. IPv6 achieves a broadcast-like result by sending a packet to a link-local multicast group address. IPv6 uses link-local multicast to communicate application specific, management, or control information to client devices on the link-local multicast network. Since link-local multicast is local to a particular wireless local area network and wireless controller, link-local multicast packets are not forwarded to remote wireless controllers or networks. Applications such as multicast Domain Name Service (mDNS) and Universal Plug and Play (UPnP) stop working after a roaming client stops receiving their link-local multicast control information.